JPH04246261A - Fuel injection controller for diesel engine - Google Patents

Abstract

PURPOSE:To provide the fuel controller for a Diesel engine which reduces the generation quantity of smoke in a high loaded operation by properly controlling the injection pressure. CONSTITUTION:A Diesel engine is equipped with an intake swirl varying mechanism and a fuel injection system which is equipped with an electric control type injector and a fuel pressure adjusting mechanism, and performs setting to the weak intake swirl in the case of a low loaded state, while performing setting to the strong intake swirl in the case of a high loaded state, and the injection pressure is set high as the engine revolution speed is lower, and the intake flow speed is lower, and the intake swirl is weaker in case of the high loaded state, and the mixing of the injected mist and air is accelerated through the atomization of the injected mist and the increase of the injection angle, and the generation of smoke is suppressed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control system for a diesel engine, and more particularly to one that reduces smoke during high-load operation.

0002

[Prior Art] Particulates (fine particles) contained in diesel engine exhaust gas mainly consist of soluble organic components (unburned HC) and smoke, and there is a particular need to reduce these unburned HC and smoke. However, effective countermeasures have not yet been established.

As shown in FIG. 11, when the load is low, the gas temperature in the combustion chamber is low, so the amount of unburned HC emitted is large, but the amount of smoke emitted is small because the amount of fuel injection is small and the amount of air is excessive. On the other hand, when the load is high, the combustion chamber gas temperature is high, so the amount of unburned HC emissions is reduced, but the amount of fuel injected is large, resulting in insufficient mixing of fuel and air, and the injection period is also shortened. The amount of smoke emitted increases due to reasons such as the lengthening and slowing down of the combustion rate. Therefore, it is effective to suppress the generation of unburned HC during low loads and to suppress the generation of smoke during high loads.

[0004]In order to suppress the generation of unburned HC, it is desirable to lower the injection pressure and shorten the reach of the injected fuel. On the other hand, in order to suppress the generation of smoke, it is desirable to promote mixing of the injected fuel with air and to promote oxidation of carbon particles through high-speed combustion. On the other hand, in the past, a helical-shaped intake port was provided to generate intake swirl for mixing spray and air, and in order to suppress overswirl at low loads, intake swirl was canceled for each cylinder. A sub-intake port is provided to supply air,
A shutter valve is installed to open and close these sub-intake ports, and when the load is high, the shutter valve closes the sub-intake port to strengthen the intake swirl, and at low load, the sub-intake port is opened to suppress the intake swirl.The intake swirl is variable. The mechanism is also in practical use.

Recently, in order to improve fuel injection control, for example, as shown in Japanese Unexamined Patent Publication No. 2-37152, a high-pressure fuel pump, an accumulator for accumulating pressurized fuel, and pressurized fuel in the accumulator have been added to the fuel supply system. A unit injector with an electromagnetic switching valve that injects fuel based on the received pressure, and an electromagnetic relief valve that adjusts the fuel pressure in the accumulator, that is, the injection pressure, are installed, and the injection pressure is determined by the engine speed and accelerator opening or engine load. There are known devices that change depending on the situation.

[0006]

[Problem to be Solved by the Invention] In the prior art, such as the unit injector type fuel injection control device of the above-mentioned publication, the injection pressure is determined according to the operating condition determined by the engine rotation speed and the accelerator opening. The system employs control that determines the injection period based on the fuel injection amount. By the way, during high-load operation, the injection pressure is usually set high to promote mixing of the spray and air.If the injection pressure is increased, the spray angle of the injected fuel becomes larger, but at high rotation speeds, the intake flow velocity is large and the intake swirl is strong, so if the spray angle becomes too large, the sprays will overlap and the amount of smoke generated will increase due to poor mixing of the sprays and air. On the other hand, at low engine speeds, the intake flow velocity is low, so the intake swirl is weak, and the amount of smoke generated increases due to poor mixing of spray and air.

An object of the present invention is to provide a fuel injection control device for a diesel engine that can reduce the amount of smoke generated during high loads.

[0008]

[Means for Solving the Problems] A fuel injection control device for a diesel engine according to claim 1, as shown in the functional block diagram of FIG. In a diesel engine equipped with a variable means and an operating state detecting means for detecting an operating state defined by engine speed and load, the intake air is adjusted during high-load operation based on the operating state detected by the operating state detecting means. The apparatus is equipped with an injection pressure control means that sets the injection pressure higher through the injection pressure variable means as the flow velocity becomes lower.

A fuel injection control device for a diesel engine according to a second aspect of the present invention is the fuel injection control device for a diesel engine according to the first aspect, wherein the injection pressure control means controls the injection as the engine speed decreases during high-load operation. It is configured to set a high pressure.

As shown in the functional block diagram of FIG. 10, the fuel injection control device for a diesel engine according to a third aspect of the present invention includes an injection pressure variable means that is installed in the fuel supply line and can adjust the injection pressure, and a A diesel engine equipped with an intake swirl variable means for setting the strength of the intake swirl to be weak during low-load operation and strong during high-load operation, and an operating state detection means for detecting an operating state specified by engine speed and load. The engine is equipped with an injection pressure control means that sets the injection pressure higher through the injection pressure variable means as the intake swirl becomes weaker during high-load operation based on the operating state detected by the operating state detection means.

The fuel injection control device for a diesel engine according to a fourth aspect of the present invention is the fuel injection control device for a diesel engine according to the third aspect, wherein the injection pressure control means is configured to control the injection pressure when the engine speed is low compared to when the engine speed is high. The injection pressure is also configured to be set high.

00012

[Operation] The fuel injection control device for a diesel engine according to claim 1 includes an injection pressure variable means which is interposed in the fuel supply line and is capable of adjusting the injection pressure, and an operating state defined by the engine speed and load. Based on the operating state detected by the operating state detecting means, the injection pressure control means controls the injection pressure control means to increase the injection pressure as the intake flow rate is lower during high-load operation via the injection pressure variable means. Since the pressure is set high, the lower the intake flow velocity and the weaker the intake swirl in the combustion chamber, that is, the less mixing of the spray and air, the higher the injection pressure is set to atomize the spray and improve the spray. By increasing the spray angle, mixing of the spray and air can be promoted and smoke generation can be suppressed.

[00013] In the fuel injection control device for a diesel engine according to the second aspect, basically the same effect as that in the first aspect can be obtained. In addition, the injection pressure control means is configured to set the injection pressure higher as the engine speed decreases during high-load operation, so that when the engine speed is low during high-load operation, the intake swirl is weak and the spray and air When mixing with the air becomes insufficient, the injection pressure is set high to atomize the spray, and the spray angle is increased to promote mixing of the spray and air, suppressing the generation of smoke. You can.

In the fuel injection control device for a diesel engine according to claim 3, there is provided an injection pressure variable means which is interposed in the fuel supply line and is capable of adjusting the injection pressure, and the strength of the intake swirl in the combustion chamber is controlled during low load operation. An intake swirl variable means is provided which sets the intake swirl to be weak at times and strong at high load operation, and based on the operating condition detected by the operating condition detection means, the injection pressure control means controls the injection so that the intake swirl is weaker during high load operation. Since the injection pressure is set high through the pressure variable means, as in claim 1, the injection pressure is set higher as the intake swirl in the combustion chamber becomes weaker, that is, the mixing of spray and air becomes insufficient. This makes it possible to atomize the spray and increase the spray angle of the spray to promote mixing of the spray and air, thereby suppressing the generation of smoke.

[00015] In the fuel injection control device for a diesel engine according to the fourth aspect, basically the same effect as that in the third aspect can be obtained. In addition, the injection pressure control means is configured to set the injection pressure higher when the engine speed is low than when the engine speed is high, so that the injection pressure is set higher when the engine speed is low than when the engine speed is high. By setting the pressure high and increasing the spray angle, mixing of the spray and air can be promoted and smoke generation can be suppressed. Furthermore, it is possible to prevent an increase in the amount of smoke generated due to overlapping of sprays caused by excessive injection pressure resulting in an excessive spray angle when the intake air flow rate is high and the intake swirl is strong at high engine speeds.

00016

According to the fuel injection control device for a diesel engine according to claim 1, as explained in the section of the above-mentioned operation, the lower the intake flow velocity and the weaker the intake swirl in the combustion chamber, the more
In other words, the injection pressure is set so high that the mixing of the spray and air becomes insufficient, thereby atomizing the spray, and the spray angle of the spray is increased to promote mixing of the spray and air, thereby preventing the generation of smoke. can be suppressed and fuel efficiency can be improved.

According to the fuel injection control device for a diesel engine according to the second aspect of the present invention, basically the same effects as those of the second aspect can be obtained, as explained in the section of the above-mentioned operation. In addition, when the engine speed is low during high-load operation, the injection pressure is set high to atomize the spray, and the spray angle is increased to promote mixing of the spray and air, creating smoke. can be suppressed.

According to the fuel injection control device for a diesel engine according to claim 3, as explained in the section of the operation, the weaker the intake swirl in the combustion chamber, that is, the mixing of spray and air becomes insufficient. By setting the injection pressure to a higher level, it is possible to atomize the spray and increase the spray angle to promote mixing between the spray and air, suppressing the generation of smoke, and improving fuel efficiency. I can do it.

According to the fuel injection control device for a diesel engine according to the fourth aspect, basically the same effects as those in the third aspect can be obtained, as explained in the section of the above-mentioned operation. In addition, when the intake flow rate is slow at low rotation speeds and the intake swirl is weak, the injection pressure can be set high to increase the spray angle, promoting mixing of spray and air and suppressing the generation of smoke. When the intake flow rate is high and the intake swirl is strong at high engine speeds, excessive injection pressure causes an excessive spray angle.
It is possible to prevent the amount of smoke generated from increasing due to overlapping sprays.

00020

Embodiments Examples of the present invention will be described below with reference to FIGS. 1 to 8. This embodiment is an example in which the present invention is applied to a fuel injection system for a four-cylinder in-line diesel engine for automobiles. First, the intake system and exhaust system of the diesel engine 1 will be explained based on Fig. 1.
Each cylinder 50 has an intake port opening 51 that is opened and closed by an intake valve.
and an exhaust port opening 52 that is opened and closed by an exhaust valve,
The intake ports 53 of each cylinder 50 are configured as helical intake ports that generate a counterclockwise intake swirl in FIG.
An air cleaner 56 is provided in the intake passage 55 where the intake ports 4 and 4 merge, and an air cleaner 56 is provided in the intake passage 55 where the intake ports 5 and 4 join together.
A sub-intake port 57 having a diameter smaller than that of the sub-intake port 57 is provided, and these sub-intake ports 57 are connected to a sub-intake passage 58 branched from the intake passage 55, and an electromagnetic on-off valve 59 for opening and closing the passage is interposed in the sub-intake passage 58. It is set up. The sub-intake port 57 is for suppressing intake swirl during low-load operating conditions, and is formed to supply air into the combustion chamber from a tangential direction opposing the counterclockwise intake swirl. Therefore, the main flow of intake air is supplied from the intake port 53 and generates a counterclockwise intake swirl within the combustion chamber, but when the electromagnetic on-off valve 59 is opened and air is also supplied from the sub-intake port 57, the intake flow This weakens the intake swirl inside the combustion chamber. Four branch exhaust pipes 60a of the exhaust manifold 60 are connected to exhaust ports 61, respectively. Note that instead of the electromagnetic on-off valve 59, four interlocking shutter valves that open and close each sub-intake port 57, respectively, and an electric actuator that synchronously drive these may be provided.

Next, the overall configuration of the fuel injection system will be explained based on FIG. 2. The fuel injection system of a diesel engine 1 (hereinafter referred to as engine) includes a high-pressure fuel pump 2 driven by the engine 1, and this fuel pump 2.
an electromagnetic three-way relief valve 5 interposed in a fuel passage 4 leading from the fuel pump 2 to the accumulator 3, and an accumulator connected to the accumulator 3 via a fuel supply passage 6. four sets of unit injectors 7 that inject and supply pressurized fuel supplied from 3 to the combustion chambers of the four cylinders, respectively; and a drive circuit unit 8 that supplies drive pulses to the electromagnetic switching valves of the four sets of unit injectors 7. It includes a control unit 10 and sensors. In addition, the code|symbol 9 is a fuel tank.

The sensors include a fuel pressure sensor 11 that detects the fuel pressure in the accumulator 3, a well-known crank angle sensor 12 that detects the rotation angle of the crank angle using an electromagnetic pickup sensor, and a reference timing of the reference cylinder (for example, , intake TDC) in the same manner as described above, and a potentiometer or the like that is connected to the accelerator pedal and detects the accelerator opening corresponding to the amount of accelerator depression (this corresponds to the engine load). An accelerator opening sensor 14 that detects the temperature of the engine cooling water, a water temperature sensor 15 that detects the temperature of the engine cooling water, an air temperature sensor 16 that detects the temperature of the air taken in at the upstream portion of the intake passage, and an air pressure sensor 17 that detects the air pressure are provided. Detection signals from these sensors 11 to 17 are supplied to the control unit 10, respectively. The control unit 10 is
The four unit injectors 7 are controlled by outputting a control signal to the drive circuit unit 8, and the fuel pressure in the accumulator 3, that is, the injection pressure is controlled by outputting a drive pulse to the solenoid of the electromagnetic three-way relief valve 5. .

The structure of the unit injector 7 will be briefly explained based on FIG. 2. unit injector 7
consists of an injector main body 20 and an electromagnetic switching valve 21 attached to its upper end.In the injector main body 20, a needle valve 23 is formed at the lower end of a needle valve element 22, and a needle valve 23 is formed at the lower end of the needle valve element 22.
2 is urged toward the valve closing side by a first spring 25 via a spring receiver 24, and a piston 27, a second spring 28, and a spring receiver 29 are installed in the cylinder hole 26, and is urged downward by the second spring 28. The lower end of the rod 27a of the piston 27 is connected to the spring receiver 2.
4, and the orifice 30 of the spring receiver 29 communicates with the control pressure port 31 of the electromagnetic switching valve 21. Needle valve body 22
An outlet chamber 32 is formed on the outer circumferential side of the lower half of the unit, pressurized fuel is supplied from the accumulator 3 to the outlet chamber 32 via the fuel supply path 6, and the needle valve body 22 receives the fuel pressure in the outlet chamber 32. Forced upward.

In the electromagnetic switching valve 21, the control pressure port 3
A first valve body 34 is accommodated in the upper valve hole 33 of the first valve body 34 , and the first valve body 34 is configured to be able to open and close between the control pressure port 31 and the drain passage 35 . communicates with the control pressure port 31 through a center hole 37, a second valve element 38 is slidably attached to the center of the upper end of the first valve element 34, and a center hole is connected to the lower end of the second valve element 38. 37 is configured to be openable and closable, and the second valve body 38 is urged downward by a valve closing spring 39, and when the solenoid 48 is energized, the first valve body 3
4 rises against the valve closing spring 39 to open the valve and communicate the control pressure port 31 with the drain passage 35, and at the same time, the second valve body 38 closes the center hole 37. An input port 41 is formed outside the middle part of the first valve body 34, and the input port 41 is connected to the fuel supply path 6 through an input path 42.
As shown in the figure, when the solenoid 40 is OFF and the first valve body 34 is in the closed position, the input port 41 and the inner chamber 36 are communicated through the input hole 43 of the first valve body 34 .

Therefore, when the solenoid 40 is OFF, the first valve body 34 is in the closed position and the control pressure port 31 and the drain path 35 are cut off, so that the pressurized fuel in the fuel supply path 6 is transferred to the input path. 42, input port 41, input hole 43, inner chamber 36, center hole 37, control pressure port 31, orifice 3
0, the pressure receiving chamber 26a is filled, and the piston 27 is strongly urged downward, so that the needle valve body 22 pushed by the piston 27 is at the lower limit position, and the nozzle 44 is closed by the needle valve 23, so that the fuel is not injected. On the other hand, when the solenoid 40 is energized, the first valve body 34 rises and moves to the open position, and the second valve body 38 descends relative to the first valve body 34 to close the center hole 37. , the fuel pressure in the pressure receiving chamber 26a decreases to the drain pressure, and the needle valve body 22 is raised by the fuel pressure in the outlet chamber 32, and fuel is injected from the nozzle 44.

The control unit 10 is an A/D converter for A/D converting the detection signals from the sensors 11, 14 to 17.
Converter, circuit for waveform shaping of detection signals from sensors 12 and 13, input/output interface, CPU, ROM, and R
AM, a drive circuit for the electromagnetic three-way relief valve 5, a drive circuit for the electromagnetic shut-off valve 59, etc., and the ROM contains a control program for fuel injection control to be described later and accompanying programs to be described later. A fuel injection execution control that sequentially drives the four unit injectors 7 in response to various maps (or tables or calculation formulas) and data on the injection timing and injection period determined by this fuel injection control. A control program is input and stored in advance. However, fuel injection execution control is performed using the pulse signal obtained from the crank angle sensor 12 and the reference crank angle sensor 1.
Based on the reference crank angle pulse signal and clock pulse signal from 3, the unit injector 7 constantly calculates and monitors whether each cylinder has reached the injection (start) timing, and each time the injection timing arrives, the corresponding unit injector 7 Since this is a well-known general control to execute injection during the injection period, a detailed explanation thereof will be omitted.

Next, fuel injection control for determining injection pressure, injection period, and injection timing will be explained. however,
This fuel injection control device also includes variable intake swirl control performed via an electromagnetic on-off valve 59. To explain the load of the diesel engine 1 as roughly divided into low load and high load, the amount of air supplied is large enough at low load and high load, and since the amount of fuel injection is small at low load, intake swirl occurs. If it is too strong, the spray will be diluted with air, reducing combustibility. Therefore, when the load is low, the electromagnetic on-off valve 59 is held open and the intake swirl in the combustion chamber is set weakly. Regarding the injection pressure, the injection pressure is set low in order to shorten the reach of the spray and improve combustibility.

On the other hand, since the fuel injection amount increases when the load is high, it is desirable to strengthen the intake swirl to promote mixing of spray and air, so the electromagnetic on-off valve 59 is kept closed. Regarding injection pressure, considering that the lower the engine speed, the lower the intake flow velocity and the weaker the intake swirl, the injection pressure is increased to atomize the spray and increase the spray angle, thereby reducing the interaction between the spray and the air. shall promote the mixing of

Next, a brief description will be given of the map that is stored in the ROM in advance in association with the control program for fuel injection control. The zone map in FIG. 4 includes a weak swirl zone (low-load operating region) where the electromagnetic on-off valve 59 is opened to weaken the intake swirl, and a strong swirl zone (high-load operating region) where the electromagnetic on-off valve 59 is closed to strengthen the intake swirl. ). The map of fuel injection amount Q in FIG. 5 shows an example in which the fuel injection amount Q (injection amount per injector for each injector) is set for the entire operating range using engine speed and accelerator opening as parameters. It is something.

The injection pressure map in FIG. 6 shows an example of setting the injection pressure for the entire operating range; when the engine speed is constant, the injection pressure increases as the load increases; When the load is constant, the injection pressure is set to increase as the engine speed decreases. The injection timing map in FIG. 7 shows an example of the injection timing (injection start timing) for the entire operating region using the crank angle (deg) before the compression TDC.

Next, a fuel injection control routine performed by the control unit using the above-mentioned maps will be explained with reference to the flowchart of FIG. However, Si (i=1, 2, . . . ) in the figure indicates each step. When control starts with the engine starting, necessary initial settings are executed for the RAM memory, etc. (S1), then various detection signals are read from sensors 11 to 17 (S2), and then the crank The engine speed Ne is calculated based on the angle signal (S3), and then the current operating state determined by the engine speed Ne and the detected accelerator opening is determined in the weak swirl zone (i.e., It is determined whether the load is in a low load area (S4). However, it is also possible to omit the map in FIG. 4 and make the determination based on the accelerator opening degree. Then Yes in S4
When it is determined, a drive current is output to the solenoid of the electromagnetic on-off valve 59, and the electromagnetic on-off valve 59 is held in the open state (S5). Next, the fuel injection amount Q corresponding to the current operating state is calculated using the map shown in FIG. 5 (S7). However, temperature correction and density correction are performed on the fuel injection amount Q using the air temperature and atmospheric pressure detected by the sensors 16 and 17.

Next, the injection pressure corresponding to the current operating state is calculated using the map shown in FIG. 6 (S8), and then expressed by the formula: fuel injection amount Q=constant×injection period×injection pressure. Then, the injection period is calculated by applying the determined fuel injection amount and injection pressure to the above calculation formula (S9), and then the injection timing corresponding to the current operating state is calculated using the map shown in FIG. (S10), then in S11, a drive pulse corresponding to the injection pressure is output to the solenoid of the electromagnetic three-way relief valve 5 via the drive circuit, and the fuel pressure in the accumulator 3 is adjusted to the injection pressure determined as above. The injection timing and injection period data are output to the fuel injection execution control, and then the process returns from S11 to S2.
The subsequent steps are repeated at predetermined minute intervals. In addition, in the fuel injection execution control, each time the injection timing for each cylinder comes, a drive current is supplied to the solenoid 40 of the injector 7 corresponding to that cylinder only during the injection period via the drive circuit unit 8, and fuel injection is performed. Execute.

When the current operating state enters the high load region, that is, the strong swirl zone, a negative determination is made in S4 and the process moves to S6, where the supply of drive current to the electromagnetic on-off valve 59 is stopped and the electromagnetic on-off valve 59 is stopped. is held in a closed state, and then the process moves to S7, and the steps after S7 are executed.

Next, the operation of the fuel injection control described above will be explained. During low-load operation, the overall injection pressure is set low, so the distance the injected fuel reaches is shortened, preventing the combustion temperature from decreasing due to combustion in a relatively narrow area within the combustion chamber, and preventing the cylinder and Since the amount adhering to the wall surface of the piston is reduced, the amount of unburned HC generated is significantly reduced. Since the injection pressure is set lower as the load decreases, the spray distance can be reduced as the fuel injection amount decreases, and the injection pressure can be lowered as the engine speed increases. Since we set
Deterioration in combustibility can be prevented by reducing the spray reach distance as the intake swirl becomes stronger. In addition, the electromagnetic on-off valve 59 is held open to weaken the intake swirl in the combustion chamber, making it difficult for the spray to be diluted with air, preventing deterioration in combustibility, and removing unburned HC.
can suppress the occurrence of Incidentally, since the fuel injection amount Q is also small and there is excess air, the amount of smoke generated is small.

During high-load operation, the overall injection pressure is set high and the electromagnetic on-off valve 59 is kept closed to create a strong intake swirl in the combustion chamber.
It is possible to reduce the amount of smoke generated by promoting atomization of the spray and mixing of the spray and air. As the engine speed increases and the intake swirl becomes stronger, the injection pressure is lowered and the spray angle is made smaller, which prevents smoke from overlapping the sprays and improves fuel efficiency. I can do it. The injection pressure is increased as the intake flow velocity decreases and the intake swirl weakens as the engine speed decreases, so the mixing of the spray and air decreases due to the weakening of the intake swirl, which is reduced to atomized spray. This can be compensated for by increasing the kinetic energy of the spray particles and increasing the spray angle. Since the injection pressure is increased as the load increases, that is, the fuel injection amount increases, the mixing of the spray and air is promoted by atomizing the spray, increasing the kinetic energy of the spray particles, and increasing the spray angle. It is possible to suppress smoke generation and improve fuel efficiency. In particular, when the engine speed is low and the load is in the maximum load range, a large amount of smoke tends to occur because the intake swirl is weak despite the large amount of fuel injection, but the fuel injection control of this application In this case, the injection pressure is set to be the highest in the above operating range, so the mixing of the spray and air is promoted by atomizing the spray, expanding the spray angle, and increasing the kinetic energy of the spray particles, thereby suppressing smoke generation. It is possible to improve fuel efficiency.

It is also possible to set the injection period map in advance based on the fuel injection amount map and the injection pressure map, and in this case, the step S7 can be omitted. Incidentally, instead of the electromagnetic on-off valve 59, an electromagnetic control valve capable of continuously changing the opening degree may be provided, and the opening degree may be configured to gradually decrease as the load increases in the medium load region. good. In the above embodiment, a pressure accumulating type unit injector 7 using an accumulator 3 is provided. However, instead of this, a pressure increasing type unit injector (an electrically controlled injector is provided and a plunger type fuel pump is installed in addition to this). The present invention can be similarly applied to a device that is provided with a pressure regulating means and a pressure regulating means, respectively.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an intake system and an exhaust system of a diesel engine according to an embodiment.

FIG. 2 is an overall configuration diagram of the fuel injection system of the diesel engine in FIG. 1.

FIG. 3 is a cross-sectional view of the unit injector of FIG. 1;

FIG. 4 is an explanatory diagram of a zone map.

FIG. 5 is a diagram showing a fuel injection amount map.

FIG. 6 is a diagram showing an injection pressure map.

FIG. 7 is a diagram showing an injection timing map.

FIG. 8 is a flowchart of a fuel injection control routine.

FIG. 9 is a functional block diagram of the diesel engine fuel injection control device according to the first aspect.

FIG. 10 is a functional block diagram of a diesel engine fuel injection control device according to a third aspect of the present invention.

FIG. 11 is an explanatory diagram regarding particulates contained in the exhaust gas of a diesel engine in the prior art.

[Explanation of symbols]

1 Diesel engine 2 High pressure fuel pump 3 Accumulator 5 Solenoid three-way relief valve 7 Unit injector 8 Drive circuit unit 10 Control unit 12 Crank angle sensor 14 Accelerator opening sensor 21 Solenoid switching valve 53 Intake port 57 Sub intake port 58 Sub intake passage 59 Solenoid on-off valve

Claims (4)

[Claims] 1. A diesel engine comprising: injection pressure variable means that is interposed in a fuel supply line and is capable of adjusting injection pressure; and operating state detection means that detects an operating state defined by engine speed and load. The invention is characterized by comprising an injection pressure control means that sets the injection pressure higher through the injection pressure variable means as the intake flow velocity decreases during high-load operation based on the operating state detected by the operating state detection means. Diesel engine fuel injection control device. 2. Fuel injection control for a diesel engine according to claim 1, wherein the injection pressure control means is configured to set the injection pressure higher as the engine speed decreases during high-load operation. Device. 3. Injection pressure variable means which is interposed in the fuel supply system and is capable of adjusting the injection pressure, and intake swirl variable means which sets the strength of the intake swirl in the combustion chamber to be weak during low load operation and strong during high load operation. and an operating state detecting means for detecting an operating state defined by engine speed and load, the intake swirl is controlled during high load operation based on the operating state detected by the operating state detecting means. 1. A fuel injection control device for a diesel engine, comprising injection pressure control means that sets the injection pressure higher through an injection pressure variable means as the injection pressure becomes weaker. 4. The fuel for a diesel engine according to claim 3, wherein the injection pressure control means is configured to set the injection pressure higher when the engine speed is low than when the engine speed is high. Injection control device.